1. Field of the Invention
This invention relates to an improved linear insulator for electrically insulating different electrical potentials such as exist between high voltage power lines and support structures. Insulators of this type, often referred to as rod insulators, are typically long, upwards of 10 to 15 feet, and provide high tensile strength to support heavy objects, such as large power lines which are suitable for carrying electrical potentials of 500 KV and higher. Generally, the linear insulators provide comparable insulating characteristics as the conventional porcelain insulators (see U.S. Pat. No. 1,972,613) and have improved pollution resistance (see Electrical World, Sept. 1, 1976, pages 44-45).
2. Description of the Prior Art
Conventional linear or rod insulators are fabricated as a single unit and consist of a nonconductive cylindrical linear core member and a plurality of coaxially attached nonconductive toroidal weather sheds. The core member may be fabricated out of fiberglass, epoxy, or Kevlar (trademark material) to provide the required tensile strength. The weather sheds come in a variety of shapes which are principally designed to increase the leakage path between the two electrical potentials at either end of the linear insulator, and may be fabricated out of nonconducting porcelain, ceramic, or polymer materials.
None of the prior art linear insulators with which I am familiar provides adequate protection from the build-up of atmospheric contamination and the resulting deterioration of insulating performance. Further, none of the prior art linear insulators imposes a controlled gradient of electrical potential along the body of the insulator.
U.S. Pat. No. 4,016,358 does show a series of conventional ceramic insulators with incorporated contamination and flash-over eliminators; however, no device is known which provides contamination control for the linear insulator, and no device is known which imposes a control gradient of electrical potential by a single appliance or apparatus.